As far as I know, rF2 doesn't simulate a fully live axle yet, so motion ratio is static. To loosely simulate what you want you will have to do it via the corner bump stops as you can set a base stiffness and a rising rate with compression.
Thank you for that info. I think, in the spreadsheet, you have motion ratio, and it can be varied depending on the pushrod position, however it can't be made positive (rising) due to the lack of a simulated rocker arm / secondary pivot. It s a rocker arm that I would like to simulate rather than a live axle. The bumpstop idea is very good, but may be limited when it comes to adjusting the suspension.
Yes I don't think any rocker geometry is possible at all. As you see in the physics sheet, the push/pullrod is seen as the spring/damper.
"Rising rate suspensions are not really possible without a rocker mount, so rF2 doesn't really do them properly yet." This is from one of our physics guys.
